The source says Facebook swooped in after the financing; the
billion-dollar acquisition deal was made in the last 24 hours.
Facebook wasn't part of the talks when Instagram closed its $50
million round a week prior.

Multiple sources tell us that Sequoia had no idea that Instagram
was going to sell, and was investing to help Instagram build a
long-term business. But the firm isn't exactly upset over
doubling the value of its investment in a matter of days.

AllThingsD's Liz Gannes reported that
Sequoia was close to investing in Instagram last week.